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20 August 2009 Boundary-condition dependent elasticity of short double-stranded DNA molecules
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We have measured the entropic elasticity of ds-DNA molecules ranging from 247 to 1298 base pairs in length, using axial optical force-clamp tweezers. We show that entropic end effects and excluded-volume forces become significant for such short molecules. In this geometry, the effective persistence length of the shortest molecules decreases by a factor of two compared to the established value for long molecules, and excluded-volume forces extend the molecules to about one third of their nominal contour lengths in the absence of any external forces. We interpret these results in the framework of a modified wormlike chain model.
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Yih-Fan Chen, K. Raghunathan, David Wilson, and Jens-Christian Meiners "Boundary-condition dependent elasticity of short double-stranded DNA molecules", Proc. SPIE 7400, Optical Trapping and Optical Micromanipulation VI, 740003 (20 August 2009);

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